The present invention relates generally to the refinement of lead and more specifically to the treatment of byproducts created during lead refining.
Standard industrial smelter practices have a long history of refining and purifying desirable metallic products. In order to achieve a refined or more pure metallic product, impurities must be removed, which creates byproducts. Byproducts are commonly either stored and shipped offsite, or metal is reclaimed from the byproducts through a furnace or other reclamation process. The treatment and/or disposal of byproducts add to smelter cost by either replacing production capacity as a re-circulating load or adding charges for transportation, additional processing, and disposal.
Treatment and recovery of metal from smelter byproducts has been the focus of research for well over 100 years as cited in U.S. Pat. No. 4,891,067. Closely associated with the bag house dust treatment pursued in U.S. Pat. No. 2,325,176 are the economic considerations influencing the recovery of lead, tin, and antimony bearing fumes and drosses. As is the case with most fume or dust treatment procedures, hydrometallurgical processes are used to great advantage; however, the environmental, labor, and capital costs become significant. U.S. Pat. No. 4,891,067 provides a treatment process for recovering copper, iron, gold, silver, bismuth, lead, antimony, and molybdenum along with a common environmental pollutants arsenic and sulfur.
Regardless of the type of furnace or smelting operations, the volatile metal fumes of low melting temperature nonferrous metals and their oxides are customarily captured in air/fume separation systems. Those systems include an electrostatic precipitator, bag houses, and wet and dry scrubbers. U.S. Pat. Nos. 5,679,553, 5,538,532, and 5,234,669 detail procedures using chemical and mechanical techniques for the treatment of flue or bag house dusts and drosses after the flue dust is collected.